• KIPS Transactions on Software and Data Engineering
• /
• v.7 no.12
• /
• pp.497-504
• /
• 2018

This paper studies about the Oriental Medical Expert System, based on Open Source Drools for rule engine processing, which contains scalability, availability, and modifiability. The system is developed with the Spring MVC framework and Ajax for stable services of the Web-based Medical Expert System. The diagnosis and treatment process of this Medical Expert system provides a service that provides the general users to accesses the web with a series of questionnaires. In order to compensate for the asynchronous communication between clients and services, and also for the complicated JDBC weaknesses, we applied the data handling in JSON to reduce the servers' loads, and also the Mybatis framework to improve the performance of the RDBMS, respectively. In addition, as the number of users increases to cope with the maximum available services of the web-based system, the load balancing structure using Nginx has been developed to solve the server traffic problems and the service availability has been increased. The experimental results show the stable services by approving the scalability test.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.7
• /
• pp.479-488
• /
• 2019

A cruise missile uses wings and a jet engine like an airplane to reach the target after cruising a considerable distance. An integrated design of a cruise missile based on radar cross section (RCS) reduction and enhanced aerodynamic performance is indispensable, since it must be able to fly long-distance at subsonic speed without being detected by enemy radar. In this study, we designed a Taurus-type cruise missile and analyzed its RCS and aerodynamic characteristics using the physical optics (PO) technique and the Navier-Stokes CFD code. As a result, we obtained the optimal shape of cruise missile with improved aerodynamic performance and reduced RCS.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.21 no.2
• /
• pp.119-129
• /
• 2011

TCP-related Flooding attacks still dominate Distributed Denial of Service Attack. It is a great challenge to accurately detect the TCP flood attack in hish speed network. In this paper, we propose the NIC_Cookie logic implementation, which is a kind of security offload engine against TCP-related DDoS attacks, on network interface card. NIC_Cookie has robustness against DDoS attack itself and it is independent on server OS and external network configuration. It supports not IP-based response method but packet-level response, therefore it can handle attacks of NAT-based user group. We evaluate that the latency time of NIC_Cookie logics is $7{\times}10^{-6}$ seconds and we show 2Gbps wire-speed performance through a benchmark test.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.24 no.5
• /
• pp.13-20
• /
• 2020

The effect of the relative distance between two cavity flame holders on the performance of a supersonic combustor was experimentally investigated. A rectangular cross-sectional combustor model with one cavity flame holder on each of two facing walls was used, with two difference distances between cavities of 135 mm and 220 mm. The fuel equivalence ratio was varied as 0.16 and 0.38. A direct-connected type test facility was used to provide Mach 2 flow condition. The test results revealed that the combustion pressure was higher for the shorter cavity distance case. But fuel equivalence ratio did not have large effect on the combustion pressure. It was concluded that, to get higher combustor pressure, there needs to be further combustor configuration change such as smaller cavity distance or tandem cavity installation.

• Journal of the Korean Institute of Gas
• /
• v.26 no.4
• /
• pp.1-8
• /
• 2022

DME, a clean fuel that is being studied as an alternative fuel for diesel engines, can reduce exhaust gas, which is the one of the crucial problems of diesel engines, and has a very high cetane number and high oxygen content. DME is a fuel has properties similar with LPG and can use the infrastructure of LPG. In this study, The target was to build a database of basic data on the mass flow rate discharged for the performance evaluation of the plunger-type high pressure pump. In this study, the mass flow rate of the DME plunger type high pressure pump was analyzed by changing the common rail pressure and the motor rotation speed. The experimental conditions were the common rail pressure was changed from 300 to 500 bar and the motor rotation speed was changed from 300 to 1000 rpm. In addition, basic mass flow data were constructed to high-pressure pumps for DME. As a result of the experiment, in both cases the mass flow rate was increased.

• Nuclear Engineering and Technology
• /
• v.55 no.4
• /
• pp.1233-1243
• /
• 2023

Shell-and-tube heat exchanger (STHX) is widely used by virtue of its simple structure and high reliability, especially in a space-constrained surface ship. For the STHX of the surface ship, roll, pitch and other motion of the ship will affect the heat transfer performance, resistance characteristics and structural strength of the heat exchanger. Therefore, it is urgent to carry out numerical simulation research on three-dimensional thermal hydraulic characteristics of surface ship STHX under the marine conditions. In this paper, the numerical simulation of marine shell and tube heat exchanger of surface ship was carried out using the porous media model. Firstly, the mathematical physical model and numerical method are validated based on the experimental data of a marine engine cooling water shell and tube heat exchanger. The simulation results are in good agreement with the experimental results. The prediction errors of pressure drop and heat transfer are less than 10% and 1% respectively. The effect of marine conditions on the heat transfer characteristics of the heat exchanger is investigated by introducing the additional force model of marine condition to evaluate the effect of different motion parameters on the heat transfer performance of the heat exchanger. This study could provide a reference for the optimization of marine heat exchanger design.

• Convergence Security Journal
• /
• v.23 no.5
• /
• pp.117-123
• /
• 2023

Recently, as the demand for Generative Artificial Intelligence (AI) and artificial intelligence has increased, the seriousness of misuse and abuse has emerged. However, intelligent CCTV, which maximizes detection of abnormal behavior, is of great help to prevent crime in the military and police. AI performs learning as taught by humans and then proceeds with self-learning. Since AI makes judgments according to the learned results, it is necessary to clearly understand the characteristics of learning. However, it is often difficult to visually judge strange and abnormal behaviors that are ambiguous even for humans to judge. It is very difficult to learn this with the eyes of artificial intelligence, and the result of learning is very many False Positive, False Negative, and True Negative. In response, this paper presented standards and methods for clarifying the learning of AI's strange and abnormal behaviors, and presented learning measures to maximize the judgment ability of intelligent CCTV's False Positive, False Negative, and True Negative. Through this paper, it is expected that the artificial intelligence engine performance of intelligent CCTV currently in use can be maximized, and the ratio of False Positive and False Negative can be minimized..

• Journal of the Korean Society of Propulsion Engineers
• /
• v.2 no.2
• /
• pp.64-73
• /
• 1998

In twin spool aero-engine, there may be a S shaped annular duct between high pressure and low pressure spools. The flow passing this S shaped duct experiences the flow acceleration and deceleration due to the convex and concave surface of the duct as well as the increase of blockage according to the boundary layer growth along the surfaces. So, the high pressure compressor which is located behind the S shaped duct is influenced by the non-uniform flow field generated by the geometry of inlet duct. To study the influence of the S shaped duct on the centrifugal stage, performance tests were implemented for the compressor with straight cylindrical inlet duct and with S shaped inlet duct, respectively. The test results showed that the performance, such as pressure ratio and efficiency, of the compressor with S shaped duct was worse than that of the compressor with cylindrical duct. And the compressor with S shaped duct had reduced maximum flow rate around design speed. To investigate the cause of performance degradation, flow anlaysis was performed for the impeller in front of which is located S shaped annular duct. The result of CFD showed the strong acceleration of the flow in the axial direction around the inducer tip region which caused the increase of relative mach number and the decrease of incidence angle of the flow.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.3
• /
• pp.112-118
• /
• 2018

In order to meet the strict emission regulations for internal combustion engines based on fossil fuel, the proportion of after-treatments for vehicles and vessels is gradually increasing. Diesel engines have high power, good fuel economy, and lower $CO_2$ emissions, and their market shares are increasing in commercial vehicles and passenger cars. However, NOx is generated in the localized high-temperature combustion regions, and particulate matter is formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for after-treatment of the exhaust gas to reduce NOx in diesel vehicles. This study aims to improve the NOx reduction performance of Cu SCR catalyst, which is widely used in light, medium, and heavy-duty diesel engines. The de-NOx performance of $5Cu-2ZrO_2$/93Zeolyst(Si/Al=13.7) SCR catalyst was about 5-50% higher than that of $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) at catalyst temperatures of $300^{\circ}C$ or higher. The zeolite had lower metal dispersion than zeolyst, and the reaction rate of the catalyst decreased as the average particle size increased. The $10Cu-2ZrO_2$/88Zeolyst catalyst loaded with 10wt% Cu had the highest NOx conversion rate of 40% at $200^{\circ}C$ and about 65% at $350^{\circ}C$. The ion exchange rate of Cu ions increased with that of Al, the crystalline compound of zeolite, and the de-NOx performance was improved by 20-40% compared to other catalysts.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.1
• /
• pp.118-128
• /
• 2016

As the interest on the air-pollution is gradually rising up at home and abroad, automotive and fuel researchers have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward two main issues : exhaust emission and PM (particulate matter) particle emissions of gasoline vehicle. Exhaust emission and PM particle of automotive had many problem that cause of ambient pollution, health effects. In addition, researcher studied the environment problems of the MTBE contained in the fuel as oxygenate additives. The researchers have many data about the health effects of ingestion of MTBE. However, the data support the conclusion that MTBE is a potential human carcinogen at high doses. Based on the oxygenated fuel additive types (MTBE, Bio-ETBE, Bio-ethanol, Bio-butanol), this paper discussed the influence of oxygen contents on gasoline fuel properties and evaporative emission characteristics. Also, this paper assessed the acceleration and power performance of gasoline vehicle for the fuel property.